I guess defaulting to freenode could be a good idea and the only good option here from the list. I personally don't like defaults on anything, I like to start empty and I am sure most of the older IRC users do the same but also I don't need the server list either so, the general user comes to check freenode.
OFTC is too specific just for FOSS, freenode is more general, DALnet has a more focused demographic, Rizon is an awesome network but just too weird and full of warez for a default pick.
I personally don't like this one (nor freenode) but should't Snoonet be considered as one of the major networks around today? They also have a valid cert.
The invalid certificates are just been reported as invalid but most of them are self signed, still valid for an encrypted connection of course.
